Initial screening for PKU performed on newborns before their discharge from the hospital uses a blood sample rather than a urine sample because:
A) Urine samples are more difficult to collect
B) Serum bilirubin levels are routinely measured on all newborns
C) It is easier to measure phenylalanine than phenylpyruvic acid
D) Increased serum phenylalanine can be detected earlier

Question

Quizplus · Accepted Answer

The reason why a blood sample is preferred over a urine sample is that increased serum phenylalanine can be detected earlier, allowing for early intervention and treatment of PKU. Urine samples can also be influenced by factors such as hydration status and the timing of the last feed, making blood samples more accurate for diagnosis. Serum bilirubin levels are not relevant to PKU screening, and while measuring phenylpyruvic acid is important for confirmatory testing, it is not the initial screening method used.

Initial Screening for PKU Performed on Newborns Before Their Discharge